Curtiss O-40 Raven

Flight, January 1934

A MODERN AMERICAN OBSERVATION AIRCRAFT
The Curtiss "Raven” (Wright "Cyclone F") developed for the U.S. Army Air Corps

   THE observation aircraft, as such, does not exist in the R.A.F. The work of observation is performed chiefly by the Army Co-operation Squadrons, but our general purpose and day bomber machines (we are not concerning ourselves with Fleet aircraft) can do the work when necessary. America, about 1918, tried out some D.H.4's equipped as general purpose machines, but, unlike ourselves, abandoned this type and developed several specialised classes of aircraft, of which the "observation" machine is one. A modified D.H.4 was America's first choice for the work. This type was replaced by Curtiss "Falcons" (Curtiss D.12) and Douglas O.2 biplanes ("Liberty"). At present the U.S. Army Air Corps possesses quite a "mixed bag" of observation types, including the two last mentioned machines, Thomas Morse biplanes and Douglas high-wing monoplanes. Of the batch of new types being tried out, one, the Curtiss "Raven" (YO-40A), is of particular interest. Five "Ravens" have been ordered by the U.S. Army Air Corps for service tests.
   The "Raven" is a sesquiplane with a very pronounced sweep back on the wings. The small lower plane gives the pilot and observer an excellent view forward and downward. The wings are of metal construction and are covered with fabric. Frise ailerons are used; these are fitted to the top plane only.
   The fuselage is an all-metal monocoque structure. All the tail surfaces are of metal, the fin and tail plane being metal covered. Both rudder and elevator are covered with fabric and are fitted with Flettner balances. As may be seen from the photograph, the tandem cockpits are well sheltered for gunnery and observation work. The pilot is provided with a fixed machine gun and 200 rounds of ammunition. The gun is mounted in the top starboard plane and fires outside the periphery of the airscrew blades: this arrangement obviates the complications of synchronising gear. The observer's gun is mounted on a special curved track round the rear of the cockpit. Five hundred rounds of ammunition are provided. Among the normal equipment carried by the "Raven" may be mentioned wireless transmitting and receiving apparatus, camera, observation flares and a Driggs-Faber signalling pistol. It has been reported by the U.S. Army Air Corps that the "Raven" has one of the best observers' cockpits ever developed.
   Perhaps the most interesting feature of the "Raven" is the undercarriage. The wheels retract inward and upward near the junction of the lower planes with the fuselage. The pilot is informed of the position of the wheels by a system of signals. The complications of the retractor gear do not prohibit the use of brakes, which in this case are of the Bendix variety. The steerable tail wheel swivels through 360 deg.
   The latest version of the "Raven" is fitted with a Wright "Cyclone F" engine of 700 h.p. which drives a three-bladed metal airscrew. The ring-type engine mounting is of welded-steel tubes. As in the case of large numbers of military aircraft, the "Raven" is fitted with a "droppable" petrol tank.
   From time to time various modifications have been made to the "Raven," as, for example, alterations in the shape of the cockpit hooding and wheel fairings. Such changes, of course, will affect the performance of the machine. According to data issued in 1932, the top speed at sea level is 196 m.p.h., and 187 m.p.h. at 15,000 ft. The climb to 15,000 ft. takes 11 min., and the absolute ceiling is 26,800 ft. With normal fuel load the range is 230 miles, but the tankage may be increased to lengthen this to 430 miles.
   Main dimensions of the ''Raven'' are as follow: - Span of top plane, 43 ft. 11 in.; overall length, 27 ft. 9 in., and wing area, 314 sq. ft.

Flight, August 1934

AMERICAN MILITARY MONOPLANES

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Also of the Corps Observation class, but not of monoplane design, is the new Curtiss "Raven," or O-40, with the Wright "Cyclone" F engine of 700 h.p. This is a two-seater sesquiplane with transparent hooded cockpits and a retractable landing gear, which give it a high speed of 200 miles an hour. The dimensions of this machine, of which a few have been delivered for service tests, are: Span (top), 43ft. 11in., and a length of 28ft. 3m. (A description was published in Flight of January 4, 1934. - ED.) A later model of the Raven, the O-40B, is a high-wing parasol monoplane.
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